Structural and Magnetic Study of Fe-Al₂₀-(Ti, Nb) Alloys

The present studies are devoted to a set of Fe80Al-based alloys in which Fe atoms are substituted by Ti (5 at.% or 8 at.%), and by 4 at.%Ti + 4 at.%Nb.The Mössbauer and magnetic observations are supported by chemical and structural analysis using scanning and transmission electron microscopy (TEM), and X-ray diffraction.The chemical compositions at all samples turn out to be in good agreement with the nominal one regardless investigated area, but certain differences are detected at sample containing Nb.In the sample modified by Ti+Nb, coherent precipitates uniformly distributed in Fe-Al-based matrix are identified by TEM.Regarding macroscopic magnetic properties the saturation magnetization decreases with increasing Ti content, however, a partial substitution of Ti by Nb evokes an opposite effect, i.e., an increase of the saturation magnetization by 87.5%.All ternary and quaternary alloys yield a higher temperature stability of magnetic properties as compare to the parent Fe80Al20.The Mössbauer results confirm the dominant ferromagnetic phase and the accompanied paramagnetic phase.Their relative amounts depend on the Ti and Nb alloying.The changes in magnetic microstructure are reflected in hyperfine parameters.